If you're having issues with your GPS navigation or Google Maps on your LG G5, this could either be due to a software issue or the GPS antenna in your phone. Most of the time it's a software issue and you can resolve it by modifying the following settings:

Go to Settings > Location (in the General tab

Tap on "Mode"

Select "High accuracy"

If changing your location mode doesn't work, you can download an application from the Google play store named "GPS Status and toolbox" to help increase your GPS accuracy even further and help your phone find a GPS satellite faster.

If you're still having issues after setting the accuracy to High and downloading the GPS Status app, it might be a hardware issue with the GPS antenna. The best indication of a hardware issue is if the GPS Status app is unable to locate any satellites to connect to. Consider sending your LG G5 for repair through your Carrier or going to a repair shop.